Musicians Roadhouse

I bought some tung-sol kt66's for my 2466. The bottom of the tube is very flat and they have a metal band (see photo below). I was told they won't work with the tube clips (see photo below) on the 2466. My question is: can I safely remove the tube clips or should I get a different set of tubes? That's for your help, Steve.

tung-sol tube:


tube clip:


marshall tube:

You may want to wait for a reply from Steve D to make sure, but they should work. You will have to take the bear claw retainers off. That should be fine in the head version, but if you move the amp alot just buy some spring type retainers.On some amps like my Fenders, you need to put the screw back in to firmly hold the socket. I do not know how this is for the VM. The metal base on the one you picture is like that of a KT 88. JJ KT66 use a KT88 base and they work in the VM if you remove the bear claws. I did a little looking for you and go to the following to see a detailed description of what you really have. Google --the tube store---go under KT66---go under reviews----go under Templetons KT66 review and it wil show the brands and the descriptions. It mentions with your tubes some siminlarities to 6L6 with a KT88 base and basically describes them as a 6550. That is not necessarily a bad thing as far as tone. Maybe Steve D or others can give insight as to weather or not it will affect function properly and work well in the VM. From what is basically described it sounds like they will work, just may be a little different. I would wait till others chime in before running them in your amp and get some more info though, so you can make an informed decision. I just provided the information to the review to give you a better idea what you have. Good Luck!

Dave W wrote:You may want to wait for a reply from Steve D to make sure, but they should work. You will have to take the bear claw retainers off. That should be fine in the head version, but if you move the amp alot just buy some spring type retainers.On some amps like my Fenders, you need to put the screw back in to firmly hold the socket. I do not know how this is for the VM. The metal base on the one you picture is like that of a KT 88. JJ KT66 use a KT88 base and they work in the VM if you remove the bear claws. I did a little looking for you and go to the following to see a detailed description of what you really have. Google --the tube store---go under KT66---go under reviews----go under Templetons KT66 review and it wil show the brands and the descriptions. It mentions with your tubes some siminlarities to 6L6 with a KT88 base and basically describes them as a 6550. That is not necessarily a bad thing as far as tone. Maybe Steve D or others can give insight as to weather or not it will affect function properly and work well in the VM. From what is basically described it sounds like they will work, just may be a little different. I would wait till others chime in before running them in your amp and get some more info though, so you can make an informed decision. I just provided the information to the review to give you a better idea what you have. Good Luck!

If I remove the clips and put the screws back the tube does not fully "seat" in the socket. That's why I'm wondering if I could remove the clips and the screws. If not, I'll have to see if I can return the tubes to Musicians Friend.

the clamps and the screws are there to retain the valve and that's that. removing the clamps and screws will make no difference to the amp. you can use any kt66 tubes you fancy.

I would check with Musicians Friend first. Look under their return policy and see if they take tubes back on return, some companies do not. Think about what you paid for them and the cost to ship back and the hassle. Think about the reviews of this brand and see if you are willing to keep them if you can use them.
So, you made me curoius if a tube with a metal KT88 base really can fit in the VM with the clips and screws removed? I took the back off mine just now and took the clips off and see where putting the screws back on may affect how the tube sits if the bases are big and flat. I took the screws out. It feels pretty sturdy. It seems like the sockets are secured on one side from the inside as when I pressed on the socket it was firm on one side and had a tiny amount of play opposite of that. The sockets clearly sit about 1/8 inch above the metal chassis so thats good. Unless you are using a bias probe you will have to take the chassis out of the amp to set the bias for the new tubes sowhile you are diong that see how the sockets are secured, it may help your decision to move forward or not. I think that you would be fine to use the tubes in the sockets without the screws as long as you were gentle when placing them in. I am assuming you have the head and not the combo. If you want them more secure, order some spring tube retainers and maybe the screws will be a little flatter. I felt the screws for the retainers were pretty thick. Maybe even find some tiny screws with flatter heads? sounds like a little hassle but it may work. Even without any screws, I really cannot see the tubes moving around much in a head, even with moving the head often. See if anyone chimes in with some more info to help out, then you can decided what is the best route to go.

I could have sworn Steve said that the tubes with Metal bottoms will short out

I believe that they could possibly short ot if the metal bottom touches the chassis. Some like the JJ have the metal base internally grounded/linked to pin #1. That is why you have to remove the bear claw from what I read, its to make it fit and to prevent any problems with the amo too. There looks to be ample room between the base and the chassis and it looks like the very base of those tubes may be plastic too. Lets see if any more responses though, but I agree with a couple of posts previuos where it was stated take the clamps and screes off and you can use any KT66 you want.

its right that the clamp and screws are there to hold the valve in place and removing them is ok, but as said earlier i also recall an issue about metal base valves, i think the issue was with the clamp causing a short so removal of the clamp and screws should solve that, but i would wait and see what Steve has to say tomorrow, just to be safe :lol:

spikei wrote:the clamps and the screws are there to retain the valve and that's that. removing the clamps and screws will make no difference to the amp.

:!: The clamps are there to hold the valves in place but the screws are there to hold the clamp in place AND secure the valve bases to the chassis. If the screws aren't refixed after removing the retainer clamps then the power amp PCB is structurally compromised. :!:

SteveD wrote:

spikei wrote:the clamps and the screws are there to retain the valve and that's that. removing the clamps and screws will make no difference to the amp.

:!: The clamps are there to hold the valves in place but the screws are there to hold the clamp in place AND secure the valve bases to the chassis. If the screws aren't refixed after removing the retainer clamps then the power amp PCB is structurally compromised. :!:

That's what I was afraid of. Thanks for the info, Steve. I'll be returning the tung-sols for another brand on Monday.

Pentas, Golden Lions, Valve Art, GTs are all acceptable KT-66 replacements if you cannot find original Marshall tubes. I currently have Valve Art in mine and really like them.

surfnorthwest wrote:Pentas, Golden Lions, Valve Art, GTs are all acceptable KT-66 replacements if you cannot find original Marshall tubes. I currently have Valve Art in mine and really like them.

Thanks. I'll have to check and see if they've got any of those.

An old topic but I just want to say that if you refixe the screw you can plug Tung Sol TK66.
You just have to put spring retainers (#combo). A 2mm space is visible but It works quite good with pin's good contact.
I do it since one year and no bad issues with these Tung Sol KT66. (I never red this topic before...)
But Steve, if there is another reason to not use Tung Sol KT66, please tell me and I change them.
Sorry for these old topic.